This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. With aging, impairments in the pituitary-gonadal axis are associated with loss of muscle mass and function and accumulation of upper body fat. We tested the hypothesis that physiologic supplementation with testosterone and growth hormone together improves body composition and muscle function in 65-90 year-old men with low testosterone and IGF-1 levels. This was a factorial (2X3) two tiered, randomized, double masked investigation conducted at three university research centers located in the western, central and eastern United States. We enrolled 122 community dwelling men 70.8[unreadable]4.2 years-of-age with BMI=27.4[unreadable]3.4kg/m2, testosterone d19.1nmol/L (550ng/dL) and IGF-1 in lower adult tertile (d21.9nmol/L=167ng/dL). The interventions included transdermal testosterone (5g or 10g/day) during suppression of endogenous testosterone with leuprolide acetate (7.5mg/monthly) and growth hormone (0, 3, or 5ug/kg/day) for 16 weeks.